In recent years, color displays of image in liquid crystal television sets, personal computers of lap top type and so on have been advanced by the development of multicolor display devices comprising a linear electrode-simple matrix, time-sharing drive or an active matrix drive wherein every picture element is incorporated with a thin film transistor (TFT).
Some of these developments have already been merchandised as a small size color liquid crystal television set.
These multicolor display devices use color filters having films of coloring matter in the three primary colors of RGB. Conventionally, the color filters have been manufactured according to various methods. For example, the dyeing method (Japanese Patent Application Laid-Open No. 55301/1985), the printing method (Japanese Patent Application Laid-Open No. 46325/1983 and Japanese Patent Application Laid-Open No. 29225/1984), the pigment dispersion method (Japanese Patent Application Laid-Open No. 237403/1985), the electrodeposition method (Japanese Patent Application Laid-Open No. 270730/1986), the vapor deposition method (Japanese Patent Application Laid-Open No. 166607/1980), the micellar disruption method (Japanese Patent Application Laid-Open No. 243298/1988 and Japanese Patent Application Laid-Open No. 50538/1988 through PCT) and so on have been known. The color filters thus manufactured have widely been used as the liquid crystal display material in liquid crystal television sets (Japanese Patent Application Laid-Open No. 7886/1986), personal computers of lap top type (Japanese Patent Application Laid-Open No. 105613/1985) and so on.
Meanwhile, liquid crystal projectors such as liquid crystal television projector, overhead projector and video projector have attracted attention as a large size display apparatus to replace color CRTs, and their development has been sped up in recent years. There have been known two types of liquid crystal projector. One of them is a projector of single plate type (Japanese Patent Application Laid-Open No. 41086/1985) and another a projector of three plate type (Japanese Patent Application Laid-Open No. 306792/1988 ). However, the devices of single plate type have a short life because of conventional color filters all of which are poor in light resistance and it is necessary that these devices be improved so as to prolong the service life. On the other hand, the liquid crystal projectors of three plate type have the drawbacks that their manufacturing cost is at a high side because they have to have an equivalent to 3 sets each of optical system and dichroic mirror and that the optical system is a complicated one.
Thus, it is necessary that a color filter excellent in light resistance be developed. Liquid crystal projectors of single plate type capable of using strong light sources will be made available by the use of color filters having excellent light resistance if such color filters come true. In addition, liquid crystal panels for overhead projector and for car will be permitted to use strong backlighting with the improved color filters, to have elevated reliability and a significantly longer life.
In color filters, the light is shielded respectively in part of the wavelengths ascribed to every color to generate the heat. Accordingly, highly bright light sources applied to color filters gives rise to the elevation of temperatures on the surface of the color filters. If still brighter light sources are used to obtain clearer pictures, the temperatures on the surface of the color filters are brought up even higher, and thus light resistance under further elevated temperature conditions is required.
Conventionally, it has been known that mixed systems of pigments denoted by the following Color Index Pigment Number (C.I.P.) are used as the organic pigment of color filters having high light resistance as disclosed in Japanese Patent Application Laid-Open No. 89906/1987:
:9, 97, 122, 123, 149, 168, 177, 180, 192, 215 216, 217, 220, 223, 224, 226, 227, 228, 240 PA1 Yellow (Y) :20, 24, 86, 93, 109, 110, 117, 125, 137, 138, 147, 148, 153, 154, 166, 168 PA1 Green (G) :7, 36 PA1 Blue (B) : 15, 15:6, 22, 60, 64 PA1 Violet (V) : 19, 23, 30, 37, 40, 50
However, liquid crystal projectors developed recently have a 3.about.5 inch panel to be magnified to the size of 40.about.200 inches, and it is necessary to project on the panels by the use of very strong light sources. It is known that projections are converged with microlenses attached to picture element. In these liquid crystal projectors, the projections are converged in this way, requiring the passage of the light of 100,000 lux or more through color filters, and it is impossible that all of above-mentioned organic pigments can withstand the use of light sources as strong as above. Thus, a color filter resistant to light sources of 100,000 lux or more, preferably 500,000 lux or more and more preferably 1,000,000 or more is desired. The necessity is particularly urgent in the red and green colors which are susceptible to the quick deterioration.